Self-digging military tank



April 5, 1955 R. H. WENDT 2,705,378

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April 5, 1955 R. H. wENDT SELF-DIGGING MILITARY TANK Filed March 7, 19512 SheetsSheet 2 Mmm 255 INVENToR.

United States Patent O SELF-DIGGING MILITARY TANK Robert H. Wendt,Evanston, Ill.

Application March 7, 1951, Serial No. 214,310

6 Claims. (Cl. 37-80) The present invention relates to self-diggingtanks, and is particularly concerned with the provision of an improvedconstruction of military tank which is adapted to protect itself whenlocated on suitable terrain by digging a hole in which the tank istemporarily located, and depressed below the surface of the terrain.

One of the most elective ways of protecting any fort or lightingapparatus, or defense installation is to dig into the earth.

One of the objects of the present invention is to utilize the presentequipment of a military tank for digging a hole in which the tank may betemporarily located, so that as much as half of the lower part of thetank may be protected against tire.

Another object of the invention is the provision of a tank constructionby means of which the tank can be turned about within its own perimeterwithout the laborious turning action of the treads, when used in drivingthe treads in opposite directions to eifect a turning, and by means ofwhich the tank may be turned so quickly that it may be unnecessary toprovide a turret.

Another object of the invention is the provision of an improved tankconstruction, which is adapted not only to dig a hole large enough tosink the tank into the earth a substantial amount for its protection,but which is also adapted to make a suitable cavity in the earth withinwhich the tank itself may turn, thereby giving it greater rotarymobility while protected at least in its lower part against counteriire.

Another object of the invention is the provision of an improved diggermechanism for military tanks, by means of which the earth beneath thetank may be engaged and thrown outwardly about the perimeter of the tankto form an embankment which provides additional protection over thatalready provided by sinking the tank into a hole.

Other objects and advantages of the invention will be apparent from `thefollowing description and the accompanying drawings, in which similarcharacters of reference indicate similar parts throughout the severalviews.

Referring to the two sheets of drawings accompanying the specification,

Fig. l is a diagrammatic side elevational view of a military tankembodying the invention;

Fig. 2 is a rear elevational View;

Fig. 3 is a top plan View showing the shape of the hole which can be duginto the earth by the use of the present apparatus;

Fig. 4 is a diagrammatic elevational view showing the tank in the courseof digging by means of its caterpillar treads, while being supportedmainly by means of a combined turntable and rotary digging memberbetween the treads;

Fig. 5 is a bottom plan view of the digging apparatus;

Fig. 6 is a vertical sectional view taken through the hydraulic plungerand turntable, which also serves as a support for the tank and is adigging mechanism;

Fig. 7 is a fragmentary side elevational detail view of the tread shoes,diggers and Scrapers;

Fig. 8 is a view in perspective of a digger tooth member; and

Fig. 9 is a view in perspective of a digger scraping member.

Referring to Figure l, 10 indicates in its entirety a military tankwhich is provided with a pair of crawler type treads 11 and 12,supported on each side of the tank 2,705,378 Patented Apr. 5, 1955 icebody 13, by means of a multiplicity of tread supporting wheels 14-24.

Each of the crawler type treads 11, 12 comprises a multiplicity ofpivotally mounted and pivotally joined sections 25, which may be of anydesired construction except that the tread members are provided with amultiplicity of backwardly extending digger and scraper members 25a and25b, respectively.

These digger and scraper members project downward and backwardly intothe terrain, and may also be of assistance in providing a better gripfor forward movement, but their main purpose is for the purpose ofdigging into and scraping up earth and throwing it out behind the treadsduring the digging operation.

In order to accomplish such a digging action it is only necessary toprovide other means of support for the tank so that the weight may belifted from the endless type treags, while the teeth are still permittedto dig into the eart The drive for the tank may comprise Diesel orinternal combustion engines with suitable gear shifts and clutches,whereby either one of the treads may be driven in either direction or inopposite directions simultaneously, or in reverse simultaneously.However, I prefer to utilize the motion of the tread for digging whichit takes when the tank is moving forward, because modern tanks may bemade to move at 40 miles per hour or more, at which speed the treadwould be adapted to dig and throw the earth backward most effectively.

Alternate digger and scraper members 25a, 25b may be used and pivoted onthe same pintles that join the tread members. When not used the diggersand scrapers lie recessed in the tread members, but the diggers andScrapers pivot down by gravity to digging position when tread is lifted.(See Fig. 7.)

The tank body is provided with a centrally located hydraulic cylinder 27and piston or plunger 28, for rotatably and reciprocably supporting acombined rotary digger and turntable 36. The rotary digger and turntable36 may be of sufficient diameter to utilize practically all the spacebetween the treads 11 and 12, and it has a circular base 29, which isprovided with a multiplicity of digging teeth 30 and backwardly turnedcentrifugal blades 31.

The turntable base 29 has the multiple blades 31 turned backwardlytoward their outer ends with respect to the direction of rotation,indicated by the arrow 32, so that the earth may slide olf the bladesmore readily due to centrifugal action, to be thrown forwardly andbackwardly between the treads 11 and 12.

The multiple scraping teeth 30 may be located in series radially andhave their edges 33 extending downwardly -and forwardly in the directionof rotation, so that they will dig into the earth and raise and loosenit.

Suitable fixed guards 34, 35 may be carried by the bottom of the tankbody 13 for keeping the earth which is impelled by the rotary digger 36from being thrown into the tread mechanism, and confining the motion ofthe earth to forward and backward directions.

The turntable 36 is supported upon the cylinder 27, which may beprovided with longitudinally extending gear teeth 37, for engagementwith the driving pinion 38, so that the turntable can be rotated as wellas reciprocated.

Various other equivalent mechanisms will suggest themselves to thoseskilled in the art for permitting the combined rotary and reciprocatingmotions either separately or simultaneously.

The plunger 28 may have a supporting base 39 at its upper end secured tothe tank body and provided with a piston 41 for use in raising theturntable by means of inlet 43, which applies hydraulic uid above piston41 and lifts cylinder 27.

The engine of the tank drives a suitable pump for producing pressure ina hydraulic tluid, such as an oil pump, which pumps the oil underpressure into a reservoir. The oil under pressure is controlled by atwo-way valve, which either shuts olf the oil circulation between upperand lower cylinder spaces, or directs the oil into the upper space at 43to lift the turntable, or into the lower cylinder space at 42 to depressthe turntable.

Thus the turntable or digger 36 may be raised or lowered at will; andthe pinion 38 may also be provided with a suitable transmission andclutches controlling its drive, so that the turntable 36 may be rotatedin either direction at low speed, or in the digging direction at afairly high speed.

The operation of the invention is as follows:

Ordinarily the combined turntable and digger 36 is retracted up betweenthe treads to the uppermost position in Fig. 2.

When the tank has arrived upon suitable terrain, which includes almostany kind of soil except that having rocks too large to be dislodged bythe present digging mechanism, the turntable may be projected downwardto the position of Fig. 4 until it engages the earth and lifts the majorportion of the weight of the tank off the treads, but 1'the diggerblades or teeth 26 are still engaging the eart Then the treads may bedriven as if for forward motion, with the treads passing backwardlyunder the tank at a fairly high speed, and the teeth may be thus causedto dig into the earth and carry it backward and upward, throwing it backof the tank.

This digging action may be continued while the turntableplunger isretracted into the tank, and the turntable permits the tank to sinkfarther and farther downward as the teeth of the treads dig away theearth beneath them.

If it is desired to dig in with the greatest of expedition the treadswill be kept pointing constantly in the same direction, and after thetreads have accomplished a suitable amount of digging the turntable willbe retracted until the weight is borne by the treads, and the turntablewill be rotated in the direction of the arrow of Figure 5, so that itsteeth may dig into the earth beneath the turntable and remove that earthto a predetermined depth.

During this digging action of-the turntable the earth is loosened by theteeth and brought up into engagement with the blades 31, which throw theearth out in a forward and backward direction, but at the same time, asthe turntable only covers a limited area, it is desirable to cause thetank to progress forward and backward alternately on its treads so thatthe turntable may dig away all of the earth which is located between thetreads forkover an area corresponding to the full length of the tan Inthis way by alternately operating the turntable to dig and the treads todo their digging, a depression may be made in which the tank may be sunkand the tank may be further fortified by the earthworks which are thrownup behind it.

Another mode of operation is to rotate the turntable slowly relative tothe tank body while the turntable is supporting the weight of the tankand while the treads are moving backward underneath the tank at highspeed.

In this case the treads will dig over an area which is annular in shapeand which is adapted to imbed all portions of the tank, except theturntable area, in a circular depression. The rotation of the tankcauses the treads to dig and throw the earth backward in all directions,and the earth will be thrown up behind the tank about the periphery ofthe depression to form a mound of earth, which will likewise afford someprotection to the tank.

After the tank has been suitably depressed in a circular depression byoperating the treads as diggers while the tank is rotated by means ofthe turntable, the turntable may then be retracted sufficiently so thatthe weight may be borne by the treads, and the turntable may be rotatedat a high speed to dig up and throw out the earth beneath the turntable.

While the treads then support the weight of the tank the turntable maybe fed downward to dig away the earth under the turntable to the samedepth as has been previously accomplished by the treads.

During the turntable digging the treads may also be used to cause thetank to progress forward and backward, thus more etfectively cleaningout the dirt from the area between the treads.

The present mechanism may be most conveniently used to imbed the tankdown to a point where the treads are covered with armor, and thus theentrenchment of the tank is adapted to protect the most vulnerable partof the tank, leaving only the upper armored part and turret, if any,exposed.

The depression in which the tank is entrenched, when circular asdescribed, may also be used in combination with one or more suitableescape hatches 45, located for- 85 wardly and rearwardly of the tankbody between the treads at a low level.

Tankmen escaping through these low hatches may crawl around the tank inthe circular depression, until this depression is made big enough bymoving the tank back and forth during a digging operation, and they mayescape from the side of the depression which is most likely to be freeof the enemy.

Another useful feature of the present construction is that by means ofthe turntable the tank may be reversed in position or pointed in anydirection quickly by moving the turntable down, supporting the weightand turning the tank on the turntable.

Larger guns than those usually supported upon turrets may be mounted onthe tank body, as indicated at 46, and these guns may be directed in anydirection by rotating the tank upon its turntable. Thus the turret maybe eliminated and the construction of the tank simplified while itsmaneuverability is increased by using the turntable to turn the tankinstead of driving one tread forward while the other one goes backwardto elect the turning.

It will thus be observed that I h ave` invented an improved militarytank construction by'means'of which the tank may entrench itself in asuitable terrain, so that all of its lower portions are protected bybeing dug in.

The tank can walk out of such a depression in a similar manner to whichit now climbs hills and other declivities, and the tank may be used alsofor digging entrenchments to be used by the personnel after the tank hasmoved out of the depression to a new position. The circular depressiondug by the tank may also be used by personnel who are following andaccompanying the tank for the protection of personnel as well asmilitary equipment.

While I have illustrated a preferred embodiment of my invention, manymodifications may be made without departing from the spirit of theinvention, and I do not wish to be limited to the precise details ofconstruction set forth, but desire to avail myself of all changes withinthe scope of the appended claims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United tates, is:

l. In a self-digging tank, the combination of a tank body provided witha pair of tank endless treads, comprising a plurality of articulatedmembers, said treads being mounted upon the opposite sides of said tankbody upon a plurality of rotatable supporting wheels carried by saidbody, and each of said treads being provided with one or more diggerteeth extending outwardly and backwardly for scraping the earth beneaththe tread and carrying it backward, and means carried by said body forsupporting the weight of said tank while the treads are operating incontact with the lsoil at a substantially high speed to engage and carryand throw the earth backwardly and upwardly from a position below thetank.

2. In a self-digging tank, the combination of a tank body provided witha pair of tank endless treads, comprising a plurality of articulatedmembers, said treads being mounted upon the opposite sides of said tankbody upon a plurality of rotatable supporting wheels carried by saidbody, and each of said treads being provided with one or more diggerteeth extending outwardly and backwardly for scraping the earth beneaththe tread and carrying it backward, and means carried by said body forsupporting the weight of said tank while the treads are operating incontact with the soil at a substantially high speed to engage and carryand throw the earth backwardly and upwardly from a position below thetank, said means comprising a supporting base provided with a columnextending centrally of said tank into the body thereof, and having forcemultiplying means for lifting the tank by means of said base and column.

3. In a self-digging tank, the combination of a tank body provided witha pair of tank endless treads, comprising a plurality of articulatedmembers, said treads being mounted upon the opposite sides of said tankbody upon a plurality of rotatable supporting wheels carried by saidbody, and each of said treads being provided with one or more diggerteeth extending outwardly and backwardly for scraping the earth beneaththe tread and carrying it backward, and means carried by said body forsupporting the weight of said tank while the treads are operatingincontact with the soil at a substantially high speed to engage and carryand throw the earth backwardly and upwardly from a position below thetank, said means comprising a supporting base provided with a columnextending centrally of said tank into the body thereof, and having forcemultiplying means for lifting the tank by means of said base and column,said column being provided with a hydraulic cylinder and plunger for itsforce multiplying lifting means.

4. In a self-digging tank, the combination of a tank body provided witha pair of tank endless treads, coinprising a plurality of articulatedmembers, said treads being mounted upon the opposite sides of said tankbody upon a plurality of rotatable supporting wheels carried by saidbody, and each of said treads being provided with one or more diggerteeth extending outwardly and backwardly for scraping the earth beneaththe tread and carrying it backward, and means carried by said body forsupporting the weight of said tank while the treads are operating incontact with the soil at a substantially high speed to engage and carryand throw the earth backwardly and upwardly from a position below thetank, said means comprising a supporting base provided with a columnextending centrally of said tank into the body thereof, and having forcemultiplying means for lifting the tank by means of said base 'andcolumn, said base and column comprising a"-rotata`bl'e turntable uponwhich the entire tank may be rotated to reverse its position or todirect it more quickly in a different direction.

5. In a self-digging tank, the combination of a tank body provided witha pair of tank endless treads, comprising a plurality of articulatedmembers, said treads being mounted upon the opposite sides of said tankbody upon a plurality of rotatable supporting wheels carried by saidbody, and each of said treads being provided with one or more diggerteeth extending outwardly and backwardly for scraping the earth beneaththe tread and carrying it backward, and means carried by said body forsupporting the weight of said tank while the treads are operating incontact with the soil at a substantially high speed to engage and carryand throw the earth backwardly and upwardly from a position below thetank, said means comprising a supporting base provided with a columnextending centrally of said tank into the body thereof, and having forcemultiplying means for lifting the tank by means of said base and column,said base and column comprising a rotatable turntable upon which thetank may be rotated while its treads are digging to cause the treads todig over a full circular area for entrenching the tank while extendingin any direction.

6. In a self-digging tank, the combination of a tank body provided witha pair of tank endless treads, coinprising a plurality of articulatedmembers, said treads being mounted upon the opposite sides of said tankbody upon a plurality of rotatable supporting wheels carried by saidbody, and each of said treads being provided with one or more diggerteeth extending outwardly and backwardly for scraping the earth beneaththe tread and carrying it backward, and means carried by said body forsupporting the weight of said tank while the treads are operating incontact with the soil at a substantially high speed to engage and carryand throw the earth backwardly and upwardly from a position below thetank, said means comprising a supporting base provided with a columnextending centrally of said tank into the body thereof, and

having force multiplying means for lifting the tank by means of saidbase and column, said base and column comprising a rotatable turntableupon which the tank `may be rotated while its treads are digging tocausethe treads to dig over a full circular area for entrenching thetank while extending in any direction, and said vturntable beingprovided with digger teeth and outwardly extending impeller vanes fordigging the earth beneath the turntable and throwing it radially frombeneath the turntable.

References Cited in the tile of this patent UNITED STATES PATENTS1,166,820 Doherty Jan. 4, 1916 1,179,750 ORourke Apr. 18, 1916 1,365,748Thorn Jan. 18, 1921 1,396,625 Corrigan Nov. 8, 1921 1,406,349 CorriganFeb. 14, 1922 1,866,037 Heim et al. July 5, 1932 2,069,797 Zublin Feb.9, 1937 2,501,083 Owen Mar. 21, 1950

